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Biomedical subjects

K Nakahara

Publications and source records attributed to K Nakahara.

At least 19 recordsLinked to original sources
PubMed1992

A comparative structural characterization of the human NSCL-1 and NSCL-2 genes. Two basic helix-loop-helix genes expressed in the developing nervous system.

Human cDNA clones for NSCL-1 and NSCL-2, two basic domain helix-loop-helix (bHLH) genes expressed predominantly in the developing nervous system, were obtained from a fetal brain cDNA library. The full-length transcripts and the genomic structures were determined. The cDNAs for the two genes encode predicted proteins of similar size (133 and 135 amino acids for NSCL-1 and NSCL-2, respectively) and structure. The carboxyl-terminal 75 amino acids of the two proteins contain the bHLH motif and differ from each other by only three conservative amino acid changes, while the amino-terminal portions are markedly divergent from each other. In addition to the similar protein structure, the genes have a similar genomic organization, suggesting a close evolutionary relationship. The 5'-regulatory regions of the two genes share some features (i.e. potential TATA, CCAAT, and GATA binding sites) but also differ significantly in their G+C content. NSCL-1 is relatively G+C-rich (63%) in the sequences upstream of transcription initiation and has multiple potential binding sites for transcription factors that bind to G+C-rich sequences (e.g. AP-2). NSCL-2 is relatively A+T-rich (63%) in this region and has a potential binding site for AP1. Studies of expression in normal tissues demonstrated expression of NSCL-1 and NSCL-2 in the developing central and peripheral nervous system, most likely in developing neurons. Additional Northern analysis studies in cell lines revealed expression of these genes in some cell lines derived from tumors with neural or neuroendocrine features such as neuroblastoma, PNET, and small cell lung cancer. NSCL-1 is expressed in a larger number of these cell lines. The differences in expression may parallel differences in developmental regulation.

Amino Acid Sequence↗
PubMed1992

Heterogeneity in smooth muscle cell population accumulating in the neointimas and the media of poststenotic dilatation of the rabbit carotid artery.

Rabbit smooth muscles contain at least three types of myosin heavy chain (MHC) isoforms; SM1, SM2 and SMemb (NMHC-B), the expression of which is developmentally regulated. We have recently reported that smooth muscles with the embryonic phenotype accumulate in the neointimas produced by endothelial denudation or high-cholesterol feeding. In this study, we examined MHC isoform expression in the neointimas and the media of poststenotic dilatation of the rabbit carotid artery, and determined the phenotype of the smooth muscle cell in the dilated segment. We report here that neointimal cells in the dilated segment are smooth muscle cells with the embryonic phenotype as previously reported in our ballooning-injury study. The medial smooth muscles, however, are composed of heterogeneous population of smooth muscles which differ in stage of differentiation as determined by the MHC isoform expression. These results indicate that MHC isoforms are useful molecular markers to identify abnormally proliferating smooth muscles in diseased arteries and to understand the process of atherogenesis occurring following vascular injury.

Angioplasty, Balloon↗
PubMed1992

Identification of three types of PDGF-A chain gene transcripts in rabbit vascular smooth muscle and their regulated expression during development and by angiotensin II.

PDGF-like peptides secreted from smooth muscles have been suggested to be responsible for the smooth muscle growth. In order to elucidate the nature of PDGF-like molecules expressed in vascular smooth muscles, we have isolated and characterized cDNA clones for PDGF-A chain from a rabbit embryonic aorta cDNA library. One of the cDNA clones was found to encode a novel PDGF-A chain, named PDGF-A3 in this report. PDGF-A3 arises from a single PDGF-A chain gene by alternative RNA splicing and differs from the sequences of previously reported endothelial- or the glioma-type transcripts by a 110 bp insertion. Expression of PDGF-A3 mRNA was selectively induced by Angiotensin II in the smooth muscle cell in vitro. Total PDGF-A mRNA is most enriched in embryonic aortas, but its expression is down-regulated with vascular development. PDGF-A mRNA is markedly increased in primary-cultured smooth muscle cells during the log-phase growth. Our results suggest that autocrine production of PDGF-A chains from the smooth muscle cell may play a role in early vascular development and in Angiotensin II-induced smooth muscle cell proliferation.

Aging↗
PubMed1992

A novel primer extension method to detect the number of CAG repeats in the androgen receptor gene in families with X-linked spinal and bulbar muscular atrophy.

X-linked spinal and bulbar muscular atrophy (SBMA), an adult-onset form of motor neuron disease, was recently reported to be caused by amplification of the CAG repeats in the androgen receptor gene. We report here a simple and rapid strategy to detect the precise number of the CAGs. After the DNA fragment containing the CAG repeats is amplified by the polymerase chain reaction, a primer extension is carried out; the extension of the end-labelled reverse primer adjacent to 3' end of CAG repeats stops at the first T after CAG repeats with the incorporation of dideoxy ATP in the reaction mixture. The resultant primer products are analysed by denaturing polyacrylamide gel electrophoresis and autoradiography. This method could be quite useful to detect not only CAG repeats in SBMA but also other polymorphic dinucleotide and trinucleotide repeats.

Adult↗
PubMed1992

CD45 isoform expression during T cell development in the thymus.

Various isoforms of leukocyte common antigen, or CD45, are expressed differentially on T cells at different stages of development and activation. We report studies on CD45 isoform expression on various subsets of human T cells using two- and three-color flow cytometry and cell depletion. Bone marrow cells that were depleted of CD3+ and HLA-DR+ cells were CD45RA-RO-. The earliest CD3-CD4-CD8-CD19- thymocytes were CD45RO- with 20%-30% CD45RA+ cells. The most prominent population of CD4+CD8+ double-positive thymocytes were CD45RA-RO+. Even the CD4+CD8+ blasts were greater than 90% CD45RO+. About 80% of single-positive thymocytes (CD4+CD8- or CD4-CD8+) were also CD45RO+. Only 4.3% of CD4+ and 18% of CD8+ single-positive thymocytes were CD45RA+. In contrast, cord blood T cells which represent the stage that immediately follows single-positive thymocytes, contained 90% CD45RA+ cells. Thus, in terms of CD45 isoform expression, single-positive thymocytes are more like double-positive cells than cord blood T cells. These results suggest the following sequence of CD45 isoform switching during T cell development: CD45RA-RO- or RA+RO- (double-negative thymocytes)----RA-RO+ (double-positive and most single-positive thymocytes)----RA+RO- (cord blood T cells), the last switch from CD45RO to CD45RA occurring as a final step of maturation in the thymus.

Antigens, CD↗
PubMed1992

CD45RA-R0+ subset is the major population of dividing thymocytes in the human.

CD45, or leukocyte common antigen, is expressed in different isoforms on different subsets of thymocytes, suggesting its involvement in the process of T cell development in the thymus. We report studies on CD45 isoform expression on human thymocytes at various stages of development using three-color flow cytometric analysis and cell cycle analysis. Among CD45R0+ cells 18.4% were in S+G2/M phase and represented more than 80% of the dividing cells in the thymus. Among the CD45R0- cells 10.9% were also in cell cycle. Because the CD45R0+ population is almost exclusively CD45RA-, the CD45RA-R0+ subset constitutes the major portion of dividing cells in the thymus. Both the CD1high and the CD3- populations were actively cycling. However, the former was almost 100% and the latter only 50% CD45RA-R0+. Dividing CD45RA-R0+ cells contain, therefore, many cells that have not yet expressed the CD3/T cell receptor complex and presumably have not yet undergone selective procedures. These results are hard to reconcile with the previously presented hypothesis that CD45R0 represents a marker for cells that are destined to die in the thymus. Instead, these results suggest an alternative possibility that CD45R0+ cells may contain cells that can mature and, thus, also constitute the thymic generative lineage.

Antigens, CD↗
PubMed1992

The SCL gene product: a positive regulator of erythroid differentiation.

The SCL (tal-1, TCL5) gene is a member of the basic domain, helix-loop-helix (bHLH) class of putative transcription factors. We found that (i) the SCL promoter for exon Ia contains a potential recognition site for GATA-binding transcription factors, (ii) SCL mRNA is expressed in all erythroid tissues and cell lines examined, and (iii) SCL mRNA increases upon induced differentiation of murine erythroleukemia (MEL) cells, and inferred that SCL may play a physiologic role in erythroid differentiation. We used gel shift and transfection assays to demonstrate that the GATA motif in the SCL promoter binds GATA-1 (and GATA-2), and also mediates transcriptional transactivation. To identify a role for SCL in erythroid differentiation, we generated stable transfectants of MEL and K562 (a human chronic myelogenous leukemia cell line that can differentiate along the erythroid pathway) cells overexpressing wild-type, antisense or mutant SCL cDNA. Increasing the level of SCL expression in two independent MEL lines (F4-6 and C19, a 745 derivative) and K562 cells increased the rate of spontaneous (i.e. in the absence of inducer) erythroid differentiation. Conversely, induced differentiation was inhibited in MEL transfectants expressing either antisense SCL cDNA or a mutant SCL lacking the basic domain. Our experiments suggest that the SCL gene can be a target for the erythroid transcription factor GATA-1 and that the SCL gene product serves as a positive regulator of erythroid differentiation.

3T3 Cells↗
PubMed1992

Thymus cells in myasthenia gravis: a two-colour flow cytometric analysis of lymphocytes in the thymus and thymoma.

The thymus in patients with myasthenia gravis has germinal centres and the thymic lymphocytes spontaneously produce anti-acetylcholine receptor antibody in vitro. This suggests indirectly that the myasthenic thymus contains mature T and B cells that are autoreactive. We report a two colour flow cytometric analysis of the surface antigen phenotype of lymphocytes in the thymus and in thymoma in 24 patients and in 14 normal thymuses. The results show a decline in the proportion of double positive immature thymocytes with age. This process seems to be partially disrupted in patients with myasthenia gravis. In addition titres of anti-acetylcholine receptor antibody were positively correlated with the proportion of mature single positive T cells and non-T DR positive cells.

Adolescent↗
PubMed1992

Reversal of CD45R isoform switching in CD8+ T cells.

Both CD4+ and CD8+ T cells express either CD45RA or CD45R0 isoform of CD45R in an exclusive way. Recent reports have shown that CD45RA+ T cells lose CD45RA and gain CD45R0 upon activation. This switching has been suggested to be irreversible although more recently, examples of reversal of CD45R isotype switching in CD4+ T cells have been reported. We report here that freshly isolated unprimed CD8+ T cells, when activated with PHA, temporarily lose CD45RA but reexpress an intermediate level of CD45RA 2-3 weeks after activation with PHA. This reversal seems to take place much more slowly in unprimed CD4+ T cells: the majority of CD4+ T cells that had lost CD45RA and gained CD45R0 remained CD45RA-CD45R0+ in 3 weeks after the stimulation. Also, long-term CD8+ CD45RA+ T cell lines stimulated with PHA or OKT3 showed even more rapid recovery of CD45RA while PPD-specific CD4+ T cell clones retained the original CD45R0 phenotype 3 weeks after stimulation with PPD or PHA.

Antigens, CD↗
PubMed1992

Experimental simvastatin-induced myopathy in rabbits.

We induced experimental myopathy in rabbits by giving simvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor. After oral administration of simvastatin (50 mg/kg/day) for 2 weeks, serum CK was elevated in 5 of 7 rabbits; degenerating or necrotic fibers were seen in 3 rabbits. Using electromyography, myotonic discharges were found in the 2 rabbits examined. The combination of myotonic discharges, necrosis and raised serum CK levels suggests that the myopathy was induced by lesions of the muscle surface membrane.

Administration, Oral↗
PubMed1992

Responsiveness of bone marrow erythroid progenitors (CFU-E and BFU-E) to recombinant human erythropoietin (rh-Ep) in vitro in multiple myeloma.

The responsiveness of bone marrow erythroid progenitors (CFU-E and BFU-E) to recombinant human erythropoietin (rh-Ep) was investigated in vitro in 21 patients with multiple myeloma to assess the clinical usefulness of rh-Ep in this disease. CFU-E and BFU-E assays were performed by methylcellulose culture methods. The myeloma patients were divided into two groups according to the percentage of plasma cells in the bone marrow (over 50% and under 50%). Among the patients with few plasma cells, some revealed normal CFU-E and BFU-E growth at 2 units of rh-Ep, and no further increase was observed even with an increasing dose of rh-Ep. Among the other patients, more than half demonstrated a good response to rh-Ep. Among the patients with a high percentage of plasma cells, some revealed no response to rh-Ep, but there were patients with a high percentage of plasma cells in the bone marrow who had a good response to rh-Ep. High doses of rh-Ep may be clinically effective in some patients with multiple myeloma independently of the level of plasma cells in the bone marrow.

Aged↗
PubMed1992

Prediction of postoperative performance status in patients with giant bulla.

To predict the postoperative improvement in performance status after bullectomy, preoperative pulmonary function and dyspneic grade were evaluated in 20 patients with giant bulla. The patients were divided into two groups, based on postoperative performance status: group 1 consisted of 15 patients with improved status after surgery; and group 2 of five patients with worsened status after temporary improvement. To determine correlation with the groups, preoperative functional measurements such as %VC, FEV1%, MMF, PEFR, RV/TLC, delta N2, LCI, and PNCD were then analyzed by the multivariate statistic method; results of delta N2 and FEV1% showed significant correlation with the groups. Prediction of the groups based on the two measurements agreed with the actual results except in one patient. These results show that postoperative improvement in performance status of patients with giant bulla can be predicted on the basis of preoperative pulmonary function.

Adult↗
PubMed1992

Oxygen transport during incremental exercise load as a predictor of operative risk in lung cancer patients.

To evaluate functional parameters related to the morbidity and mortality after thoracotomy, exercise loading was applied in 31 lung cancer patients under right heart catheterization. The routine pulmonary function and predicted postoperative pulmonary function (ppo) parameters were also evaluated. Patients were grouped according to postoperative complications: no complications (group 1, n = 17), nonfatal complications (group 2, n = 10), and fatal complications (group 3, n = 4). In all the patients %VCppo was above 40 percent and in patients undergoing pneumonectomy, pulmonary artery mean pressure during the unilateral pulmonary artery occlusion test was below 25 mm Hg. FEV1 percent and MVV/BSA were statistically significant between groups 1 and 2 but were not between groups 1 and 3 or groups 2 and 3. The %FEV1 ppo was statistically significant between groups 1 and 2 and groups 1 and 3 but was not between groups 2 and 3. Thus, the routine pulmonary function and predicted postoperative lung function tests, although they are mandatory for screening patients who are at risk, did not definitely discriminate between patients experiencing nonfatal and fatal complications after thoracotomy. VO2/BSALa20, CILa20, O2D/BSALa20, and TPVRILa20 were statistically significant between groups 1 and 3 and groups 2 and 3: in all the group 3 patients, as well as three patients of group 1 and one of group 2, VO2/BSALa20 was below 350 ml/min/m2. On the other hand, O2D/BSALa20 was below 500 ml/min/m2 in all the group 3 patients, while it was above 560 ml/min/m2 in all patients in groups 1 and 2. O2D/BSALa20 was the only parameter that definitely discriminated between experiencing nonfatal and fatal complications. We conclude that in addition to the generally accepted functional guidelines, VO2/BSALa20 should be above 400 ml/min/m2 and O2D/BSALa20 should be above 500 ml/min/m2 in patients who will undergo thoracotomy.

Adult↗
PubMed1992

[Effects of antibiotics on the dissociation of platelet adherence in pseudothrombocytopenia].

To elucidate the effects of antibiotics on platelet adherence phenomena, we examined dissociation of platelet adherence in EDTA-dependent pseudothrombocytopenia by adding Kanamycin or Colimycin. We found the rapid dissociation of platelet adherence caused by addition of Kanamycin (20 mg) or Colimycin (20 mg) in 1 ml of EDTA-anticoagulated blood from patients with EDTA-dependent pseudothrombocytopenia. This dissociation was most remarkable in the sample treated within 30 minutes after venipuncture. When the dissociation occurred, no adherent platelet was found on microscopical examinations. Complete blood cell counts and their histogram patterns after dissociation were almost same as those just after venipuncture. The dissociation occurred as soon as the antibiotics were added and remained fairly long time. The dissociation decreased in proportion to the periods of time between venipuncture and addition of antibiotics. The dissociation was caused by many other antibiotics. However, severer damage were found morphologically by adding most of them in both histogram patterns and microscopical examinations than those of aminoglycoside or peptide antibiotics.

Adolescent↗
PubMed1992

[Phrenic nerve palsy after open heart surgery--problems in post-operative respiratory management].

We clarified the problems in respiratory management in patients with phrenic nerve palsy (PNP) after open heart surgery. From December 1988 to March 1991, 248 adult patients underwent open heart surgery with topical myocardial cooling. In these patients PNP was diagnosed in 17 patients (6.9%). Age of these patients at operation ranged from 25 to 76 years with a mean age of 57 years. 9 patients were valvular heart disease (7 were reoperation), 7 were coronary artery disease, and one patient was aortic aneurysm. PNP was diagnosed by chest roentgenogram or percutaneous phrenic nerve stimulation test (PNST). Frequency of long-term intubation (> 14 days) was higher in complete PNP patients than incomplete PNP patients. 2 patients, who were observed effort dyspnea at the time of respiratory weaning, were extubated followed by respiratory and circulatory deterioration, and were reintubated. PNP were confirmed after reintubation by PNST. These patients died of pneumonia. Another 2 patients were observed effort dyspnea during respiratory weaning, and were doubted of PNP. PNP were confirmed by PNST before extubation. After hemodynamic stabilization and respiratory physiotherapy, these patients were extubated without any trouble. One patient, who required repeated intubation, was diagnosed PNP by PNST. This patient was extubated after confirmation of improvement of PNP by follow-up PNST. The incidence of PNP was higher in patients with previous open heart surgery than without previous operation. We supposed that the dissection around the heart might be one of major cause of postoperative PNP. So, in recent 4 cases of mitral reoperation, we attempted to reach mitral valve through atrial septum with minimum dissection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Adult T-cell leukemia with Ki-1 expression].

A 64-year-old man was admitted to our hospital complaining of fever and edema in February, 1990. Lymph node biopsy revealed diffuse lymphoma pleomorphic type according to the LSG classification. On hematological examination, leukocyte count was 23,500/microliters, of which 36% abnormal lymphocytes expressing CD2, CD3, CD4 and CD25 as same as the lymph node cells. Anti-HTLV-I antibody in serum was positive. From these data, the diagnosis of adult T-cell leukemia (ATL) was made. ATL cells in the blood and lymph node expressed CD30 (Ki-1). CD30 positive ATL cells derived from the blood was increased after short-term culture. The induction of Ki-1 antigen in cell lines and short-term cultured cells from ATL patients was accompanied by the appearance of the HTLV-I related antigen. Then, we suggest that there was some relation between expression of the Ki-1 antigen and activation by HTLV-I in ATL cells.

Antigens, CD↗
PubMed1992

A 5-lipoxygenase inhibitor, FR110302, suppresses airway hyperresponsiveness and lung eosinophilia induced by Sephadex particles in rats.

To study the role of chemical mediators in airway hyperresponsiveness and simultaneous eosinophilia, we examined effects of a potent 5-lipoxygenase inhibitor FR110302 and those of prednisolone, indomethacin, platelet-activating factor (PAF) antagonist (RP-59227) and leukotriene C4 (LTC4) antagonist (ONO-1078) on airway hyperresponsiveness and lung eosinophilia induced by Sephadex particles. Sephadex G200 particles (2.5 mg/kg) were injected intravenously to rats and 3 days later the airway hyperresponsiveness to acetylcholine (ACh) and the eosinophilia in the bronchoalveolar lavage (BAL) fluids were observed. FR110302 (10 mg/kg b.i.d.p.o.) significantly suppressed both of these indicators of asthma. The amounts of immunoreactive LTB4,C4 (i-LTB4, C4) in the BAL fluid were measured by radioimmunoassay. The amounts of i-LTB4,C4 in the FR110302-treated rats were significantly less compared with that in the Sephadex-injected controls. Prednisolone completely inhibited the airway hyperresponsiveness. PAF antagonist and LTC4 antagonist partially inhibited the airway hyperresponsiveness, and indomethacin had no effect. The results indicate that 5-lipoxygenase products play important roles in the Sephadex-induced airway hyperresponsiveness and lung eosinophilia in rats.

Acetylcholine↗